Weather and Climate Ch5

  1. hydrologic cycle
    movement of water between Earth and the atmosphere
  2. evaporation
    the process whereby molecules break free of the liquid volume (opposite of condensation)
  3. condensation
    the process whereby water vapor molecules randomly collide with the water surface and bond with adjacent molecules. (opposite of evaporation)
  4. saturation
    saturation is the equilibrium resulting from the constant gains and losses of evaporation and condensation.
  5. sublimation
    the change of phase between ice and water vapor, without passing through the liquid phase (opposite of deposition)
  6. deposition
    the change of phase between water vapor and ice, without passing through the liquid phase (opposite of sublimation)
  7. Humidity
    the amount of water vapor in the air
  8. vapor pressure
    part of the total atmospheric pressure due to water vapor
  9. saturation vapor pressure
    Because there is a maximum amount of water vapor that can exist, there is a corresponding maximum amount of vapor pressure that can exist called saturation vapor pressure.
  10. absolute humidity
    the density of water vapor, expressed as the number of grams of water vapor contained in a cubic meter of air.
  11. specific humidity
    an index for representing atmospheric moisture
  12. saturation specific humidity
    Because there is a maximum amount of water vapor that can exist at a particular temperature, there is a corresponding maximum specific humidity.
  13. mixing ratio
    the measure of the mass of water vapor relative to the mass of the other gases of the atmosphere
  14. saturation mixing ratio
    the maximum possible mixing ratio
  15. relative humidity (RH)
    The amount of water vapor in the air to the maximum possible at the current temperature.
  16. dew point temperature (dew point)
    the temperature at which saturation occurs.
  17. frost point
    when the temperature at which saturation occurs is below 0 degrees C (32 degrees F), we refer to it as the frost point (as opposed to the dew point)
  18. precipitation fog
    a type of fog that develops when falling raindrops evaporate enough water vapor into the air to saturate it.
  19. steam fog
    fog that forms when cold air moves over a warmer water surface
  20. homogeneous nucleation
    [seldom if ever happens because heterogeneous nucleation happens instead] droplets form by the chance collision and bonding of water vapor molecules under supersaturated conditions.
  21. hygroscopic
  22. heterogeneous nucleation
    [often happens] the formation of water droplets onto hygroscopic partices (condensation nuclei/certain aerosols)... these particles then dissolve into the water to form a solution.
  23. condensation nuclei
    the hygroscopic particles (certain water-attracting aerosols) on which water droplets form during the process of heterogeneous nucleation.
  24. haze
    aerosols in the atmosphere that are capable of attracting water at relative humidities below 90% and forming extremely small droplets... we observe these droplets as haze.
  25. supercooled water
    water having a temperature below the melting point of ice yet still existing in a liquid form (when saturation occurs between 0 degrees C and -4 degrees C the surplus water vapor condenses to form supercooled water)
  26. ice nuclei
    (rare in the atmosphere) just as the formation of liquid droplets require condensation nuclei, the formation of ice chrystals at temperatures near 0 degrees C require ice nuclei
  27. sling psychrometer
    measures humidity (simple and most widely used), consists of a pair of thermometers.
  28. wet bulb/dry bulb thermometers
    mounted to a pivoting device, are circulated through the air, measures humidity.
  29. wet bulb depression
    the difference between wet bulb and dry bulb temperatures depending on the moisture content of the air.
  30. aspirated psychometers
    use fans to circulate air around the psychometer (as opposed to being circulated)
  31. hair hygrometer
    human hair, expands and contracts on response to relative humidity.
  32. hygrothermograph
    continuous measure of humidity
  33. heat index (apparent temperature)
    expresses the effect of high humidity and high temperatures
  34. diabatic process
    (one of 2 air temperature changes) a process in which energy is added to or removed from a system [as opposed adiabatic process]
  35. adiabatic process
    (one of 2 air temperature changes) a process in which temperature changes but no heat is added or removed from a substance [as opposed to diabatic process]
  36. second law of thermodynamics
    dictates that energy moves from regions of higher to lower temperatures.
  37. dry adiabatic lapse rate (DALR)
    the rate at which a rising parcel of unsaturated air cools
  38. lifting condensation level (LCL)
    the altitude at which condensation or deposition occurs when a parcel of air rises high enough to be cooled, lowering its temperature to the dew or frost point.
  39. saturated adiabatic lapse rate (SALR)
    the rate at which saturated air cools (saturated air cools at a slower rate than unsaturated air)
  40. environmental lapse rate (ELR)
    the vertical change in temperature through still air
  41. Dew
    liquid condensation on a surface
  42. frost
    ice chrystals on a surface (much like dew, only at temperatures below 0 degrees C)
  43. frozen dew
    dew forms at slightly above 0 degrees C, the lower temperatures come in a freeze that dew. (different from frost)
  44. radiation fogs (ground fogs)
    occur when nighttime loss of longwave radiation causes colling to the dew point.
  45. advection fogs
    form when warm, moist air travels horizontally over a cooler surface ("advection" refers to horizontal)
  46. upslope fog
    (caused by adiabatic cooling) air flows along a gently soping surface, expands and cools as it moves upwards.
  47. dew point lapse rate
    the decrease in dew point as the air rises
Card Set
Weather and Climate Ch5
Weather and Climate Ch5